Electroluminescence (EL) is the emission of light from a material in response to an electric stimulus. In a typical construct, a light emitting device is formed by sandwiching an electroluminescent material between two electrode plates. The electroluminescent material and the corresponding light emitting device is operated in dry or non-polar liquid media conditions, not in polar liquid media. The use of luminescent materials in polar liquid media has been limited only to photoluminescence, where the luminescent particles absorb higher energy light from an external light source, and re-emit the absorbed energy as longer wavelength and lower energy light. A major drawback with such applications is that the high-intensity excitation light source can produce a substantial background which overwhelms the secondary light emitted by the luminescent material. Optical filters may be used to block the excitation light from entering a light detector, however they do not fully eliminate the background. The use of optical filters is especially problematic in cases where the re-emitted light from the luminescent materials is already very weak, or there is significant overlap between the excitation and emission wavelengths.
Therefore, it is desirable to achieve improved methods for exciting electroluminescent material in polar liquid media. This section provides background information related to the present disclosure which is not necessarily prior art.